1. Field of the Invention
The present invention generally relates to materials fabrication and more specifically, to thin-film materials having low-electrical resistance for use in bolometers.
2. Description of Prior Art
A bolometric material is a material that utilizes an electrical property (such as electrical resistance) which changes with temperature, usually used by a multi-detector device for detecting and measuring small amounts of thermal radiation. To be utilized in a multi-detector device such materials must comply with both thermal and electronic requirements.
It is important that these materials be fabricated in thin-film form to lower noise and have large thermal coefficients of resistance (TCR). An electrical requirement especially for use in low-ohm resistance multi-detector devices is that the material must also have a low electrical resistance.
Bolometric materials are manufactured from many different materials by various processes. Materials used in the prior art include: semiconductors, such as carbon; mixed oxides of nickel, cobalt, and manganese; germanium doped with gallium or indium; and indium antimonide. Different forms of these materials for bolometers are known, including a class of bolometers incorporating a capacitive element using thin films with temperature dependent electrical polarization properties. For thin film manufacture of materials such as the oxides mentioned above reactive sputtering is usually utilized. Unfortunately, there is a problem in that the prior art materials which have high TCR's also have high-electrical resistivities. Another problem is that many of the thin films, such as the above mentioned oxide films, produced by reactive sputtering are difficult to reproduce because of the disastrous effects of minute changes in deposition pressure on resultant electrical conductivity.
While the prior art has reported using bolometric materials none have established a basis for a specific method that is dedicated to the task of resolving the particular problem at hand.
What is needed in this instance is a method to reduce the electrical resistance of a material while retaining thermal characteristics for bolometer use.